Characterization of chemically and electrochemically prepared polyanilines in inverse microemulsions

Abstract

Chemical polymerization of aniline in an inverse water-in-oil microemulsion medium has been performed and the resulting ultrafine polymer particles (10-35 nm) are spherical. The stoichiometries, thermal stabilities and conductivities of polyanilines prepared in both microemulsion and aqueous media are generally similar. The presence of surfactant was detected in the pre-washed polymer and it has a detrimental effect on the conductivity of the product. Considering the homogeneity of the product obtained in chemical microemulsion polymerization, the method has been applied to electropolymerization. The microemulsion method provided a denser, more uniform and compact film of higher conductivity than that produced in an aqueous medium. Apart from the doping level determined by XPS, the morphological differences between the films produced by the two polymerization media are responsible for the much higher conductivities measured for the films prepared in a microemulsion. A nucleation-initiated growth mechanism has been proposed to explain the results obtained.